There have been various definitions of screening over the years, but simply what we are talking about in screening is seeking to identify a disease or pre-disease condition in apparently healthy individuals. This concept is now widely accepted in most of the developed word. Used wisely, it can be a powerful tool in the prevention of a disease. Screening has important ethical differences from clinical practice as the health service is targeting apparently healthy people, offering to help individuals to make better informed choices about their health. The module is presenting basic theoretical background necessary for understanding the usefulness of screenings, the screening process, and potential risks, as well as it provides a case study of breastt cancer screening.